(fix) - correct Context types for useContext

Changelog.md

@@ -7,6 +7,9 @@
 - Make sure `MockedProvider` is using the proper CJS/ESM bundle, when 
   referencing `ApolloProvider`.  <br/>
   [@jure](https://github.com/jure) in [#3029](https://github.com/apollographql/react-apollo/pull/3029).
+- Adjust the `ApolloContext` definition to play a bit more nicely with 
+  `React.createContext` types.  <br/>
+  [@JoviDeCroock](https://github.com/JoviDeCroock) in [#3018](https://github.com/apollographql/react-apollo/pull/3018)
 
 ### Bug Fixes
 

src/ApolloContext.ts

@@ -7,6 +7,5 @@ export interface ApolloContextValue {
   operations?: Map<string, { query: DocumentNode; variables: any }>;
 }
 
-export const ApolloContext = React.createContext
-  ? React.createContext<ApolloContextValue | undefined>(undefined)
-  : null;
+export const ApolloContext = React.createContext &&
+  React.createContext<ApolloContextValue | undefined>(undefined)